A case of inflammatory disseminated superficial porokeratosis in a colon cancer patient.

Disseminated superficial porokeratosis (DSP) is a specific disorder of keratinization. Genetic studies show that DSP is an autosomal dominant trait. Clinically, the lesions show a sharply demarcated and hyperkeratotic plaque with central atrophy. The lesions appear mainly in the extremities and generally develop with bilateral symmetry. Unusual cases of DSP accompanied by severe pruritus have been reported as "eruptive pruritic papular porokeratosis" or "inflammatory DSP." Histopathologically, inflammatory DSP is characterized by the presence of cornoid lamella with a dense infiltration of eosinophils and lymphocytes in the perivascular area of the upper dermis. Here we report a case of inflammatory DSP in a 84-year-old man with colon cancer who presented with multiple hyperpigmented atrophic macules.